One reason for having a weblog is that it makes a handy notebook of important things to remember. For instance, I cut-and-paste from this post on reconfiguring log4j every few months.
So, to help my memory, I now committing to the Interweb the fact that DateFormat is not thread-safe, and neither is SimpleDateFormat, and I'm not the first to do so.
Now, excuse me while I code a small patch for a production application...